Device for forming sheet metal joints and seams



Jan. 6, 1970 JzH, KEMP 3,487,669

DEVICE FOR EORMING SHEET METAL JOINTS AND SEAMS Filed Sept. 20, 1967 Fig.7 Fig.8

INVENTOR Joe H. Kemp 9. IO BY 5 EATTORNEYS United States Patent US. Cl. 72-76 9 Claims ABSTRACT OF THE DISCLOSURE A rotary hammer device for working sheet metal, particularly for closing sheet metal joints of the type commonly known as Pittsburgh lock.

This invention relates to a metal working device, more particularly a power hammer type device adapted for use with a rotary power tool such as a drill, sander or the like, for bending sheet metal without scufling or otherwise damaging the sheet metal surface and without distorting or bending the metal other than to form the closure of the joint, whereby a flat seam may be provided on a job remote from a metal shop.

A particular object of the invention is to provide a sheet metal working device which is simple and economical, yet of durable construction; which is adapted to operate easily and efficiently on various gauges of sheet metal for closing and bending the metal, particularly to close a metal joint such as a Pittsburg lock with out damaging the metal; and particularly, to provide such a device which may be carried to the job for use with portable power tools such as portable electric drills, portable electric sanders, grinders or similar rotary type portable tools.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE 1 is a schematic view of an electric drill having a hammer member made in accordance with the invention attached thereto;

FIGURE 2 is an isometric view partly broken away, showing the tool in use in forming a joint by bending the edge of a piece of sheet metal to close the joint seam;

FIGURE 3 is an enlarged plan view of a modified form of the hammer member of FIGURE 1;

FIGURE 4 is a transverse sectional view taken on the line 44 of FIGURE 3;

FIGURE 5 is an enlarged fragmentary view of one of the projecting hammer elements of the hammer member! of FIGURES 1 and 3;

FIGURE 6 is an enlarged view, similar to FIGURE 5, showing a slightly modified form of hammer element;

FIGURE 7 is a view, similar to FIGURE 6, of a further modified form of the hammer device of the inven tion;

FIGURE 8 is a fragmentary sectional view taken on the line 88 of FIGURE 7;

FIGURE 9 is a fragmentary plan view of a further modified form of hammer member; and

FIGURE 10 is an enlarged fragmentary view of the projecting hammer element of FIGURE 9 taken on the line 10-40.

Various types of machines have been used in the past for forming sheet metal to close joints such as the Pittsburg lock, but most such machines have not been portable and have not provided for use in forming the sheet metal to close a joint at the job installation point. The joint of the type described is used widely in the sheet 3,487,669 Patented Jan. 6, 1970 ice metal industry to fasten opposite edges of a sheet of sheet metal together to form a duct corner, or to fasten two edges of different sheet metal together for other structures. The sheets to be joined each have their edge portions prefabricated in a particular manner, one sheet 10 (FIGURE 2) having its edge portion bent at a right angle to form a downturned flange 11, and this sheet is called the angled sheet. The other sheet 12, called the replaited sheet, has its edge portion folded back on itself to form a flat S-fold having an inner portion 13, middle portion 14, and an outer portion 15. The middle and outer folds 14 and 15 are spaced slightly from each other to form an outwardly facing channel or groove 16 which is adapted to receive the flange 11 of the flanged sheet. The outer fold 15 has its projecting end portion extending beyond the folds 13 and 14 to form a bendable flange portion 17, commonly called the outstanding edge. In forming the Pittsburg lock, the flange 11 of the flanged sheet is inserted into the channel 16 of the replaited sheet, then the projecting flange or outstanding edge 17 of the replaited sheet 12 is folded flat along the surface of the angled sheet 10 at the bend between the sheet 10 and the flange 11 along a seam line 18, so that the bent projecting flange or outstanding edge 17 lies fiat against the flange sheet 10 to close the joint lock and hold the two sheets firmly together.

Obviously, the operation of bending the flange 17 inwardly by hand, or by hammer or other tools, is a time consuming and ineflicient operation, and may result in damage to the sheet metal flange portion and provide an insecure and irregular lock joint. Reciprocating hammers have the same objection, in that they may provide an irregular joint or damage the material forming the flange. Other types of devices which are adapted to ride along the seam of the joint and press the outstanding edge into its locked position are diflicult to operate, are complex and expensive, and ordinarily can be used with only a relatively limited range of metal thickness. Also, many of the machines are not portable or are not adequately sturdy to withstand continued usage, and require considerable maintenance. The device of the invention has been designed to accomplish the objects of the invention and to solve the problems heretofore stated.

Referring to the accompanying drawings, a standard rotary tool 20 such as an electric drill, electric sander or other type portable power device, having a nose portion 21 with a rotary shaft 22 projecting therefrom, is provided with a disc-like hammer member 25 of my invention.

In its preferred form, the hammer member 25 is substntially dish-shaped, having an annular concavo-convex surface 26 on its outer periphery provided with a plurality of diameterically opposed hammer elements 27 and 28 spaced uniformly angularly about the concaveconvex surface. In FIGURES l and 2 the hammer member is provided with two hammer elements 27. In FIG- URES 3 and 4 the member 25a is provided with four hammer elements 27a. Obviously, other different numbers of hammer elemens could be provided on the member if they are spaced uniformly about the periphery of the device,

As will be seen in FIGURE 2, the rotary tool is positioned in use so that the hammer member 25 is disposed at an angle to the plane of the upper surface of the angled sheet 10 and at an angle to the projecting flange or outstanding edge 17 of the replaited sheet. As the hammer member is rotated in the direction of the arrow, the hammer elements 27 will succcessively repeatedly rapidly engage the upstanding flange portion 17 and bend the same downwardly by repeated blows as the device is moved in the direction of the upper arrow along the flange 17 until the flange closely overlies the suface of the angled plate to form a smooth uniform joint closure and lock. Since the hammer member is rotated at a relatively high speed, a large number of smaller hammer impacts or blows are transmitted by the hammer elements 27 to the sheet metal to form the same without damaging it and to provide a uniform smooth joint.

Since the outer peripheral portion 26 of the hammer member is concave-convex whereby the member is dish-shaped, and the hammer elements 27 formed on and project from annular convex surface, it will be seen that the hammer member may be readily used at an angle, so that it will provide a hammer action for all positions member and locations of the hammer elements provide for hammering close to an angle joint wherein the flange portions 17 must be bent adjacent a different section of the duct or sheet which is disposed at an angle to the surface of the sheet 10. Obviously, also, the curved convex portion 26 of the hammer member provides, by controlling the angle at which it is held with respect to the flange portion 17, for control of the force imparted to the flange portion of the sheet metal by the hammer elements 27.

As is clearly shown in FIGURES l, 2 and 3, the hammer elements 27 and 27a are formed in a substantially tear-drop shape whereby a reduced projecting portions 28 and 28a is formed at the inner portion of the hammer elements nearest the shaft, and the hammer element extends outwardly with increasing projecting size and width toward its outer portion 29. This shape provides for variation in the hammer blow which can be effected by the hammer member by varying the angle .of attack of the sheet metal flange portion 11 by the hammer elements 27, a larger and heavier blow being struck by the greater projecting portion 29a than is the case when the sheet metal is struck by the lesser projecting portion 28a. The surface of the hammer elements 27 is smoothly curved to prevent damaging the sheet metal, and may be formed of a hardened material, such as a carbide or the like, which will withstand Wear and heavy impact and usage.

The central portion 30 of the hammer member is provided with an aperture 31 by means of which the hammer member is attached to the shaft 22 of the power unit in the usual manner, by clamping the same with a bolt 22a and clamping washer 22b to the shaft of the power unit to securely grip the hammer member on the shaft for rotation thereby. The central portion is planar and recessed beyond the lower convex portion of the arcuate concave-convex outer peripheral portion 26, to prevent the central portion of the hammer member from contacting the sheet metal being formed.

As shown in FIGURES 3 and 4 the hammer member 25a may be formed with four hammer elements 27a. The hammer elements are shown in FIGURE 4 as having been formed by welding deposition of hard metal or other wear resisting material on the outer convex surface of the peripheral portion 26a of the hammer member to provide the projecting hammer element 27a. The hammer elements may be formed of tungsten carbide or similar hard material which resists wear and does not readily break or cut.

In FIGURE 6, the hammer element 27b is shown to be forged as an integral part of the hammer member 25b, and projects from the convex surface of the peripheral portion 26b of the hammer member similarly to the deposited or welded hammer element 27a of FIG- URE 5. Otherwise, the hammer member of FIGURE 6 is constructed and operates in the same manner as the forms of the member previously described. Any number of the hammer elements 27b may be formed on the convex surface of the concavo-convex outer portion 26b of the hammer member, if the same are spaced uniformly about such outer peripheral surface to provide for uniform hammering impacts as the hammer member is rotated.

FIGURE 7 and 8 show a further modified form of hammer member 250, in which the hammer elements 270 are formed by die-forming the same to provide the outwardly projecting hammer elements 270 from the disc or sheet of metal of which the hammer member 250 is formed. As shown, the hammer element 270 is die-formed from the inner concave portion outwardly of the convex portion 320 of the outer peripheral portion 26c, as shown in the figures, whereby a concave recess 33c is formed on the inside of the hammer member and the material is deformed outwardly from the convex surface to provide the projecting hammer element. This form of the invention of the device lends itself to die-stamping or press forming from single sheets or discs of metal and thus provides for more economical manufacture of the hammer member.

FIGURES 9 and 10 show a form of the hammer member in which the hammer elements 127 are formed by hardened steel balls mounted in circular apertures formed in the concave-convex outer portion 126 of the hammer member, and secured in projecting position thereon by welding as at 136. The halls are shown as mounted with their centers disposed in the plane of the annular convex surface 126 of the hammer member to provide the projecting hammer elements 127 projecting from the convex surface portion. This form of the device is utilized in the same manner as the others, but does not provide the elongate arcuate tear drop hammer surface of the forms of the hammer elements previously described.

From the foregoing, it is believed readily apparent that an economical portable forming tool or power hammer membber has been disclosed which is particularly adapted for use in forming sheet metal, more particularly for closing sheet metal joints such as Pittsburgh lock joints. It will be apparent that the device is portable, economical to form, easy to use, adapted for carrying to the job, and useable with the usual standard power tool equipment such as drills, grinders, sanders or the like.

It will also be seen that the device provides for forming a smooth completely closed undamaged bend in the sheet metal to close a, joint quickly and economically.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A metal forming tool adapted to be used to fold the sheet metal flanges to close metal joints, including: a body member having a central disc-shaped body portion having an annular dishlike convex peripheral surface portion; a plurality of projecting hammer elements disposed in uniformly spaced positions about the convex peripheral surface portion of the member and each secured to and projecting uniformly from said convex surface in exposed striking position; means formed centrally of the body portion of the body member for mounting the same on a rotary power tool for rotation thereby, whereby the plurality of exposed projecting hammer elements are moved in a circular path to engage and deform or bend a portion of a sheet of sheet metal to fold said portion to a desired position.

2. A metal shaping hammer means including: a dishlike body member having an annular convex peripheral edge surface portion and a central portion disposed in a plane spaced from the plane of the projecting convex surface of said peripheral portion; said central portion having a central aperture therein for fixing the body member to a rotary power unit; a plurality of projecting hammer elements disposed to project from the convex surface of said convex peripheral surface portion of said body member, said projecting hammer elements being disposed at uniformly angularly spaced positions about the center of said body and projecting from the outer convex surface portion of the annular peripheral edge portion, said hammer elements being substantially tear-drop in shape along the surface of the convex peripheral surface portion of the body member, with the bulbar portion of the teardrop shape disposed outwardly from the center of the body.

3. A device of the character set forth in claim 1 wherein the hammer elements are substantially tear-drop in shape along the surface of the convex peripheral surface portion of the body member, with the bulbar portion of the tear-drop shape disposed outwardly from the center of the body.

4. A device of the character set forth in claim 2 wherein the hammer element is formed on a body of hard material deposited on the convex surface of the annular outer periphertal portion of the body member and having a shape flaring outwardly from the inner portion of the hammer element toward the outer portion thereof and projecting to an increased degree from said surface from the inner portion of the body toward the outer portion thereof, then converging inwardly toward the convex surface.

5. A device of the character set forth in claim 4 wherein the hammer element is formed by forging the same integral with the body member.

6. A device of the character set forth in claim 5 wherein the body member and the hammer elements thereon are formed by die-shaping the same in the body member peripheral portion.

7. A device of the character set forth in claim 1 wherein the hammer elements comprise hard spherical inserts disposed in apertures formed at uniformly spaced points around the annular convex peripheral portion of the body member and Welded thereto with approximately half of the spherical insert projecting from the convex surface,

8. A device of the character set forth in claim 1 in combination with a portable power unit having a rotatable shaft, and means on said power unit for securing said body member to said shaft to be rotated by said shaft of said power unit.

9. A device of the character set forth in claim 2 in combination with a portable power unit having a rotatable shaft, and means on said power unit for securing said body member to said shaft to be rotated thereby.

References Cited UNITED STATES PATENTS 3,195,492 7/1965 Erickson 1l354 CHARLES W. LANHAM, Primary Examiner L. A. LARSON, Assistant Examiner 2233 UNITED STRTES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 487 669 Dated Januarx 6 1970 Inventofl Joe H. Kemp It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col 1, line 14, for "Pittsburgh" read -Pittsburg-- Col. 2, line 51, for "stntially" read -stantia11y-- Col. 3, line 12, for "hammer" read --hammering-- Col. 3, after line 12, insert --of the flange section 17. Also,

the shape of the hammer- Col. 4, line 1, for "Figure" read --Figures- Col. 4, line 33, for "membber" read -member-- Col. 4, line 35, for "Pittsburgh" read --Pittsburg-- Col. 5, line 17, for "periphertal" read --periphera1 SIGNED AND SEALED AUG 4 -1970 fiEAL) Attest:

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